The invention relates to a reflection media primarily suitable for a machine scannable information system comprising a polymer layer having a Tg of less than 75xc2x0 C. and containing matte and glossy areas.
Reflection media primarily suitable for a machine scannable information system, generically termed barcodes herein, were originally created to help grocery stores speed up the checkout process and keep better track of inventory, but the system quickly spread to all other retail products. Barcodes are used in almost all sold goods to enable fast recognition of price or information for an item. The barcode typically consists of black lines printed on a clear or white background but may comprise other indicia designed primarily for machine scanning.
The physical device to scan in barcodes can varyxe2x80x94sometimes it might be a fixed scanner that the product is passed by, while other times it may be a handheld scanner that is passed over the product. In either case, a beam of light is passed over the symbol, and the scanner determines the bars and spaces based on the how much of the light is reflected.
Unfortunately, the current barcode system has a number of drawbacks. The typical black and white barcodes take up valuable packaging space and are unattractive. Where a packaging label is small (on a pack of chewing gum for example) the barcode might take up half of the label. Because the barcode takes of space and is unattractive, it is typically only placed in one part of the package. The operator of the barcode scanning system, for example a cashier at a grocery store, has to know where the barcode is on each package to quickly scan the item. If it is a new package design or a new item, the cashier might have to turn the package over a few times to find the barcode. It would be desirable to have a barcode system that could be placed in multiple areas of the package, without taking up addition space of the label, so it is more easily scanned.
Light diffusing elements that scatter or diffuse light generally function in one of two ways: (a) as a surface light diffusing element utilizing surface roughness to refract or scatter light in a number of directions; or (b) as a bulk light diffusing element flat outer surfaces and embedded light-scattering elements. The surface light diffusing elements normally utilize the rough surface, typically with a lens, exposed to air, affording the largest possible difference in index of refraction between the material of the diffuser and the surrounding medium and, consequently, the largest angular spread for incident light. The bulk diffuser diffuses the light within the film. Examples are small particles, spheres, or air voids of a particular refractive index are embedded another material with a differing refractive index.
Diffusion is achieved by light scattering as it passes though materials with varying indexes of refraction. This scattering produces a diffusing medium for light energy. There is an inverse relationship between transmittance of light and diffusion and the optimum combination of these two parameters is desired for each application.
U.S. Pat. No. 5,852,514 (Toshima et al.) describes a light diffusing element comprising a light diffusion layer including acrylic resin and spherical particles of polymethyl methacrylate on a transparent support. Whereas this film would diffuse the light efficiently, the polymers used have high glass transmission temperatures and would therefore be difficult to melt the spherical particles completely to create glossy areas. When scanned these incompletely melted lenses would diffuse a portion of the light lowering contrast between the matte and glossy areas of the layer.
U.S. Pat. No. 3,763,779 (Plovan) discloses a method for copying an image by selectively coalescencing microporous voids in a voided film to create areas of transparency. The method has limitations in that to produce a copy in the voided film, an original must be used and the original must be of a particular material and format. It would be desirable to have a process to selectively coalesce voids using an electronic file as the template. The film has voids throughout the thickness of the film so that to make an area of the film transparent and the resulting surface glossy, the voids throughout the thickness of the film must all be coalesced or melted. This requires a substantial amount of energy making this method expensive, time consuming, and difficult.
U.S. Pat. No. 5,369,419 (Stephenson et al.) describes a thermal printing method where the amount of gloss on a media can be altered. The method uses heat to change the surface properties of gelatin, which has many disadvantages. Gelatin can not achieve high roughness averages, thereby having a low distinction between the matte and glossy areas of the media. This small distinction between the matte and glossy states lead to a low signal to noise ratio and when scanning, leading to scanning errors. Gelatin also is very delicate, scratch prone, is self-healing, tends to flow over time thus changing its surface roughness and other properties time especially in high humidity and heat, and is dissolved if placed in water. Also, gelatin has a native yellow color, is expensive, and is tacky sticking to other sheets and itself. It would be desirable to use a material that had no coloration, is more stable in environmental conditions, and could have a higher surface roughness.
U.S. Pat. No. 2,739,909 relates to a heat-sensitive recording paper by overcoating black-colored paper with a continuous thermoplastic resin material containing microscopic voids dispersed throughout the resin. The coating layer is opaque, but becomes transparent by the localized action of a stylus using either heat or pressure or both to disclose the black color of the support. There is a problem with this element in that the manner of obtaining the voids is complicated which involves carefully controlled drying conditions of emulsions. Another disadvantage with this design is that while the coating turns transparent, the surface reflectivity is not altered.
There remains a need for an improved reflection media to provide an information system that is conveniently manufactured and applied to an article.
The invention provides a reflection media comprising a polymer layer having a Tg of less than 75xc2x0 C. and containing machine scannable information in the form of matte and glossy areas.
The invention provides improved reflection media to display information through provision of selective areas of gloss and matte. Such media may be employed to provide machine scannable information such as barcodes on articles.